BAGHDAD (AP) — Royal Dutch Shell says it has officially kicked off a multibillion-dollar project to tap natural gas in Iraq’s south.

The $17 billion joint venture will gather, process and market associated gas, a by-product of producing oil, from three oil fields in the petroleum-rich province of Basra.

Iraq holds 51 percent in the 25-year partnership while Shell holds 44 percent and Japan’s Mitsubishi holds 5 percent. The gas will be used mainly for domestic energy needs, but there is also an option for exports. Wednesday’s announcement was published on Shell’s website.

Iraq burns off almost half of the 1.5 billion cubic feet per day of gas that it produces. The deal will help the country capture more than 700 million cubic feet per day of gas from three fields.